1. Field of the Invention
The present invention relates to methods and apparatus for use in a wellbore; more particularly the invention relates to methods and apparatus for expanding tubulars in a wellbore.
2. Background of the Related Art
The drilling, completion and servicing of hydrocarbon wells requires the use of strings of tubulars of various sizes in a wellbore in order to transport tools, provide a path for drilling and production fluids and to line the wellbore in order to isolate oil bearing formations and provide support to the wellbore. For example, a borehole drilled in the earth is typically lined with casing which is inserted into the well and then cemented in place. As the well is drilled to a greater depth, smaller diameter strings of casing are lowered into the wellbore and attached to the bottom of the previous string of casing. Tubulars of an ever-decreasing diameter are placed into a wellbore in a sequential order, with each subsequent string necessarily being smaller than the one before it. In each instance, a sufficient amount of space must exist in an annular area formed between the tubulars in order to facilitate the fixing, hanging and/or sealing of one tubular from another or the passage of cement or other fluid through the annulus. Typically, when one tubular is hung in a wellbore, a slip assembly is utilized between the outside of the smaller tubular and the inner surface of the larger tubular therearound. One such assembly includes moveable portions which are driven up cone-shaped members to affix the smaller tubular to the larger tubular in a wedging relationship.
Increasingly, lateral wellbores are created in wells to more fully or effectively access hydrocarbon bearing formations. These lateral wellbores are formed off of a vertical wellbore and are directed outwards through the use of a diverter, like a whipstock. After the lateral wellbores are formed, they are typically lined with a tubular creating a junction between the tubulars lining the vertical and lateral wellbores. The junction must be sealed to maintain an independent flow path in and around the wellbores. While technologies have effectively provided means for forming and lining the lateral wellbore, an effective sealing solution for the junction created at the intersection of the vertical and lateral wellbores remains a problem.
There is a need, therefore, for apparatus and methods to quickly and easily expand a tubular in a wellbore to a given diameter. There is a further need for apparatus and methods which permit a tubular of a certain diameter to be inserted into a wellbore and to subsequently permit the diameter of that tubular to be expanded in the wellbore to maximize the fluid or tool carrying capacity of the tubular or to cause the outer surface of the tubular to interfere with the inner surface of a larger tubular therearound. There is yet a further need, for methods and apparatus for expanding tubulars in a wellbore which permit one tubular to be expanded into a window formed in another tubular to create a sealing relationship. There is yet a further need for methods and apparatus permitting a tubular to be expanded into an opening in a larger tubular therearound to create a sealing relationship.